This invention relates to a network apparatus and method for forwarding a packet, and relates to a network apparatus and method for forwarding a packet for providing layer 2 VPN functions.
The VPWS (Virtual Private Wire Service) function using MPLS (Multi Protocol Label Switching) switching is one method for constructing a Layer 2 Virtual Private Network. In VPWS operation, the network apparatus functioning via Ethernet on subscriber lines receives only flow control packets defined by IEEE 802.3x, and relays all other packets. In other words, in VPWS operation the network apparatus provides layer 2 VPN service by relaying all packets other than flow control packets.
Ethernet line redundancy on the other hand is regulated by IEEE 802.3ad standard. This standard achieves line redundancy by transmitting and receiving link aggregation control packets.
The following Document 1 (in particular, 3.2.1 “PAUSE Frames”) is described in the IEEE 802.3x standard. The subsequent Document 2 is described in the IEEE 802.3ad standard. The subsequent Document 3 and Document 4 are described in the RFC (Request For Comments) of the IETF (Internet Engineering Task Force) relating to VPWS.
VPWS, as might be assumed from the title of wire service, is a service lending cable lines to carriers. VPWS therefore gives no consideration to link aggregation.
Document 1: “TechFest Ethernet Technical Summary”, the Internet<http://www.techfest.com/networking/lan/ethernet.htm>
Document 2: “Link Aggregation according to IEEE 802.3ad”, the Internet<http://www.triumf.ca/canarie/amsterdam-test/References/wp-lag-c.pdf>
Document 3: L. Martini, and three others, “Pseudowire Setup and Maintenance using the Label Distribution Protocol”, the Internet<URL:http//www.ietf.org/rfc/rfc4447.txt>
Document 4: L. Martini, and three others, “Encapsulation Methods for Transport of Ethernet Over MPLS Networks”, the Internet<URL:http//www.ietf.org/rfc/rfc4448.txt>